Table 1

Manufacturing problems as causes of supply chain disruptions

Risks to manufacture	Non-medical examples	Medical examples
Geographically concentrated manufacturing: Production concentrated in one or few locations, such that a localised disruptive event (natural or political) risks major disruption to product manufacturing13	Earthquake and tsunami in Japan, and flooding in Thailand, disrupts automotive and electronics industries in 201135	Acute sterile saline shortage after hurricane damage to manufacturing plants, 20177 Risk of medical gloves shortage due to COVID-19 lockdown in Malaysia, the home of ~65% of the global supply36
Limited numbers of manufacturers: Few manufacturers, such that events affecting a single firm (eg, disruptions or decisions) risks major disruption to product manufacturing17	Fire at Philip’s semiconductor plant in 2000 disrupts Ericson’s sole-source of chips for mobile phone production37	Critical shortage of propofol (2009–2010) as two of three suppliers left US market38 Shortages of nine childhood vaccines, 2000–2005, due to problems with the limited numbers of suppliers39
Scarcity of critical inputs: Resource inputs or parts whose scarcity risks major disruption due to non-substitutability of resources14 or tightly-coupled production arrangements (just-in-time, short-cycle manufacturing)17	Multiyear delays in production of Boeing Dreamliner due to shortage of aerospace fasteners40	Disruptions in supply of raw or bulk materials responsible for drug shortages33 Lack of meltblown, non-woven polypropylene for the production of surgical masks and N95 respirators41